Allow using env var to enable snapshot update

Author: mathieutu

src/MatchesSnapshots.php

@@ -130,11 +130,12 @@ protected function getFileSnapshotDirectory(): string
      * matched.
      *
      * Override this method it you want to use a different flag or mechanism
-     * than `-d --update-snapshots`.
+     * than `-d --update-snapshots` or `UPDATE_SNAPSHOTS=true` env var.
      */
     protected function shouldUpdateSnapshots(): bool
     {
-        return in_array('--update-snapshots', $_SERVER['argv'], true);
+        return in_array('--update-snapshots', $_SERVER['argv'], true)
+            || getenv('UPDATE_SNAPSHOTS') === 'true';
     }
 
     /*

tests/Integration/MatchesSnapshotTest.php

@@ -400,6 +400,23 @@ public function it_can_update_a_file_snapshot_with_a_different_extension()
         $this->assertFileDoesNotExist($oldSnapshot);
     }
 
+    /** @test */
+    public function it_can_update_a_snapshot_with_env_var()
+    {
+        putenv('UPDATE_SNAPSHOTS=true');
+
+        $mockTrait = $this->getMatchesSnapshotMock();
+
+        $this->expectIncompleteMatchesSnapshotTest($mockTrait, function ($mockTrait) {
+            $mockTrait->assertMatchesSnapshot('Foo');
+        });
+
+        $this->assertSnapshotMatchesExample(
+            'MatchesSnapshotTest__it_can_update_a_snapshot_with_env_var__1.txt',
+            'string_snapshot.txt'
+        );
+    }
+
     private function expectIncompleteMatchesSnapshotTest(MockObject $matchesSnapshotMock, callable $assertions)
     {
         $matchesSnapshotMock

tests/Integration/stubs/__snapshots__/MatchesSnapshotTest__it_can_update_a_snapshot_with_env_var__1.txt

@@ -0,0 +1 @@
+Bar